Adjust your phase!
Discussion
Anybody who knows about home cinema can stop reading now, this post is intended for people just starting out in this field like me. I am not a home cinema expert of any kind, but wanted to share my experience with the subwoofer phase control with others who may benefit. If I say anything out of place, feel free to correct me.
I used to have a 5.1 system many years ago which never quite hit the spot. I recently got back into it with kit that should have delivered decent results but, if I'm honest, I was initially a little disappointed with. Most of the settings on a modern surround sound system are automatically configured by the AV Receiver (AVR) but there is one rather crucial one that is not: subwoofer phase. The subwoofer phase control is located on the subwoofer itself and needs to be adjusted independently of the AVR. Most of the articles I read about the subject weren't really that clear about how to set it correctly without going into detail about using SPL meters etc. but I’ll try to describe what I did.
Ideally you want the subwoofer to be perfectly in phase with the other speakers. That is to say, that the driver moves in and out such that it creates sound waves that compliment those from the other speakers rather than detract from them. The first image shows two sounds in phase at the bottom adding up to the wave at the top (what we’re aiming for). The second image shows two sounds out of phase that cancel each other out to make no sound (even a partial cancellation will be noticeable).
When I initially set up my new system, it didn’t sound as cohesive as the demo’s I’d had in the store but I didn’t know why. It sounded like 5 small speakers and a separate subwoofer (which of course it was but it’s not supposed to sound that way). I was obsessed with the subwoofer cut-off frequency but this wasn’t really the issue. My sub was set with the phase control at zero and I initially could not hear much difference when turning it so I left it there. However, when I had some time and an empty house I set about investigating the phase setting.
The best way I found was to put one ear next to the centre channel, and one ear next to the sub. I then put on something with repeating bass / mid tones (Daft Punk is ideal). As I turned the phase control from one side to the other, I noticed that there was a small range where the bass from the sub seemed to get louder (it was very subtle though). This was the point where it started to play in phase with the centre speaker and the two added up to a louder sound. Once I had set this point, I re-ran my AVR auto setup with the microphone.
The difference in sound was huge. Suddenly it no longer sounded like a separate speaker / sub setup and it was hard to tell where the sub was located in the room. It was a much more powerful and cohesive sound, like I heard during the shop demo. I realise this is a rather long post but I hope that for many people who may have been disappointed by their new surround sound setup this might help. Also for people who may be happy with what they have, might be able to make it even better.
I used to have a 5.1 system many years ago which never quite hit the spot. I recently got back into it with kit that should have delivered decent results but, if I'm honest, I was initially a little disappointed with. Most of the settings on a modern surround sound system are automatically configured by the AV Receiver (AVR) but there is one rather crucial one that is not: subwoofer phase. The subwoofer phase control is located on the subwoofer itself and needs to be adjusted independently of the AVR. Most of the articles I read about the subject weren't really that clear about how to set it correctly without going into detail about using SPL meters etc. but I’ll try to describe what I did.
Ideally you want the subwoofer to be perfectly in phase with the other speakers. That is to say, that the driver moves in and out such that it creates sound waves that compliment those from the other speakers rather than detract from them. The first image shows two sounds in phase at the bottom adding up to the wave at the top (what we’re aiming for). The second image shows two sounds out of phase that cancel each other out to make no sound (even a partial cancellation will be noticeable).
When I initially set up my new system, it didn’t sound as cohesive as the demo’s I’d had in the store but I didn’t know why. It sounded like 5 small speakers and a separate subwoofer (which of course it was but it’s not supposed to sound that way). I was obsessed with the subwoofer cut-off frequency but this wasn’t really the issue. My sub was set with the phase control at zero and I initially could not hear much difference when turning it so I left it there. However, when I had some time and an empty house I set about investigating the phase setting.
The best way I found was to put one ear next to the centre channel, and one ear next to the sub. I then put on something with repeating bass / mid tones (Daft Punk is ideal). As I turned the phase control from one side to the other, I noticed that there was a small range where the bass from the sub seemed to get louder (it was very subtle though). This was the point where it started to play in phase with the centre speaker and the two added up to a louder sound. Once I had set this point, I re-ran my AVR auto setup with the microphone.
The difference in sound was huge. Suddenly it no longer sounded like a separate speaker / sub setup and it was hard to tell where the sub was located in the room. It was a much more powerful and cohesive sound, like I heard during the shop demo. I realise this is a rather long post but I hope that for many people who may have been disappointed by their new surround sound setup this might help. Also for people who may be happy with what they have, might be able to make it even better.
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